Effect of trapezoidal plasma density region in bubble wakefield acceleration

• Published in: Physica scripta 2024-07, Vol.99 (7)
• Main Authors: Malik, Hitendra K, Kumar, Sonu, Singh, Dhananjay K
• Format: Article
• Language: English
• Subjects: bubble wakefield acceleration; laser wakefield acceleration; plasma; Poynting flux; trapezoidal density profile
• ISSN: 0031-8949; 1402-4896
• DOI: 10.1088/1402-4896/ad4fe7

In the process of bubble wakefield acceleration highly nonlinear region is developed inside plasma, which intuitively suggests that nonuniform plasma density having gradients may be more suited to achieve large nonlinearity in the system. Moreover, when an intense laser pulse propagates in a plasma, it is subjected to various instabilities and these instabilities can be controlled by plasma density profiles which effectively control the energy and flux of the accelerated particles. Considering all these points we investigate in the present work the scaling effect of up-ramp and down-ramp regions in plasma density profile on the bubble wakefield. These regions are separated by a plateau region (maximum density) enabling the density to have trapezoidal profile. With this density profile, the bubble wakefield acceleration is examined considering four different lengths of up-ramp and plateau regions keeping a constant down-ramp length. Increasing steepness of up-ramp length (larger density gradient), i.e., lowering the length of up-ramp and increasing the plateau length creates a bubble having higher wakefield strength, resulting into higher accumulation of plasma electrons at its tail and higher energy spectrum with higher kinetic energy gradient and Poynting flux of accelerated electrons.